Category: How-to

We at the Secret Society of Lathe Trolls are proud that one of our recent members, Andrew Turney (aka Gyro on this site), with his team at Gyro Constructivists of Aukland, New Zealand…

…was responsible for last year’s technological stunt, the Beck’s “Edison Beer Bottle” Cylinder Record. That is to say, it is a glass beer bottle that is also a playable audio record, much in the manner of Edison’s cylinder player. The latter of which, as you might know, was the earliest invention that recorded playable audio (circa 1877).

The chat thread in which the process’s evolution was discussed and reported on can be found here. We were honored to be asked to be a part of the virtual roundtable brainstorm discussions on how best to approach this challenge. It is unclear as to whether or not our input actually played any significant role in Gyro Constructivists’ eventual triumph, but a triumph it was, and a fun one.

What follows is Gyro’s summary report, which appeared previously on our site here. (The creative agency which hired Gyro Constructivists was Shine Limited.)

The Making of Beck’s Edison Bottle
Andrew Turney, Gyro Constructivists

Having seen footage of a hard drive actuator arm play music, when connected to an amplifier, convinced us we could invert the process and use the actuator as the cutter head once we mounted an appropriate cutting tip. Effectively, reverse engineering from the digital realm to create an analogue result.

Other factors in that influenced our approach –having spoken with other cutters and scouring the web– included:

• Cutting a mono recording; this allows for higher output levels with less chance of the stylus skipping in the deeper frequencies.
• Coating the bottle and all our test platters and cylinders with nitro-cellulose paint, as has been the industry standard since the 1940’s, rather than cutting directly into a solid substrate.
• Utilising a small engineering lathe, we retro-fitted a speed controller that precisely locked the the rotational and tracking speeds of the cutting arm.

Cutting head and arm:
We stripped 8 hard drives down to ascertain the most appropriate actuator for our application.

The arm from a 4″ drive as opposed to a 2.5″ drive allows more current, resulting in greater amplitude; this equals higher volume.

We built three versions of the cutting head, gaining improvements at every step.

A Google search revealed a patent listing that confirmed the problem of an audio dropout at around 8khz, due to harmonic resonance, introduced by the mechanical clamping of the tiny bearing between the arm and drive housing. We eliminated the bearing altogether, replacing it with a machined piece of flat aluminium clamped to the head between thin rubber shims.

The Cutting tool
Initially, following advice, we used a standard stylus as used on 78rpm recordings, being three times bigger than the later microgroove, keeping the engineering out of the truly microscopic realm. But we were not getting a good retrieval of the upper frequencies, so we opted to use a microgroove cut. This also gave us a little over 3 mins of audio onto the bottle, rather than less under 2 minutes with a standard groove. Also the downforce is much less, resulting in less heat input to the cutting tip and less current required. The coils on the head were smoking in some tests!

We ground a high-speed steel cutting tool which we polished to mirror finish, resulting in a very quiet cut… all this taking place under a microscope! We also have a couple of sapphire tips which we used for some test cuts, but we found the steel one are quieter but with a much shorter life. In fact any contaminants in the coating would take a microscopic chunk out of the tip effectively destroying it!

Heating the tip by winding hair-thin NiChrome wire and passing a current through it resulted in a smoother cut, requiring less downforce and reduced surface noise, as it helps it glide through the surface without tearing the substrate. Every time the downforce, cutting speed or heat adjustments were made, recalibration and equalization of the audio was required. Many days were spent resolving this.

Surface Substrates and Coatings
Initially we cut onto polycarbonate and acrylic to test the feasibility of using a hard drive actuator. This proved the principle but a lot of surface noise was present. We spent the first few weeks of test cuts onto acrylic platters, coated in Nitro-cellulose, mounted on a high torque custom built turntable.

Clear nitrocellulose was successful once a the correct amount of castor oil was established, again through trial and error. We continued with this formula thoughout the remainder of the project.

Sound Engineering
Using Garageband, we applied the RIAA equalisation curve, a filter that reduces the low frequencies and increases high frequencies. This is reversed by the phono input in playback through the amplifier. Further equalisation was needed to cancel out resonances and harmonics introduced by the cutting head and arm. Tone Sweeps of 50hz>5000khz were used for the test cuts, allowing us to adjust the equalization throughout the frequency range.

We cut scores of tracks in the quest for the greatest dynamic range and least amount of surface noise, monitoring through 15″ Tannoy Moniter Gold speakers.

Cutting the Groove
Many of the above developments gave us incremental improvements to upper frequency ranges, but we achieved a big improvement by recording at a quarter speed, and subsequently 1/8 speed. This way the cutter head didn’t need to achieve these high frequencies in real time in order to cut them onto the record. Consequently the cutting time for the track was a very tense 26 minutes.

Using small tube mounted close to the cutter, we vacuumed away the swarf as it peeled off the surface; should it come in contact with the hot cutting tip, it would instantly bake on.

To control the actuator’s movements, damping was attempted with various materials; a more powerful spring was able to temper the actuator’s large movements without reducing fast ones. This introduced resonances and harmonics which were removed prior to recording by software equalization.

We experimented with damping the cutting head initially with blue tack (as Gum was used in the middle of the last century). We then mounted a silicone oil filled trough to the arm with a paddle attached to the head and later to the arm itself, this being easily tuneable by adjusting the size of the paddle and viscosity of the silicone.

Adding up to a kilo of ballast to the cutting arm made further improvements.

We also mounted a cartridge to the end of the cutting tip to monitor the audio as was cut real time, also allowing us to compare the difference quality between the cutter and the resulting groove when played back.

Each cut was scrutinised under a microscope to inspect the smoothness and profile of the groove, and to check the cutting tip for damage.

The Player
Once we had the final bottle with it’s audio track cut into the surface coating we designed and constructed a player from black acrylic sheet, laser cut from a file drawn up in the 3D.

Much of what we learned through the build of the cutter we applied to the player. Special attention was made to eliminate any unwanted noise being introduced by motor noise, bearings and resonances from the tone arm and casing of the player itself.

The Edison Bottle made its public debut at SemiPermanent in Auckland in May to a standing ovation from the assembled media and design community.

Great cutting resource: The Secret Society of Lathe Trolls

Links:
Shine Unimited’s Beck’s Beer Bottle page
Vimeo video of project (same as embedded video at top)
Gyro Constructivists website
Gyro Constructivists’ Facebook page

Credits to:
Andrew Turney, Rob Askew & Tom Beeston – Gyro Constructivists
John Baker – Real Groovy
Peter King – Lathe Cut Records
Fred Koke – Retrotronics Auckland
Brian Harris and Chris Davison
Robert Stebbing – Stebbings Recording Centre

More links on this project:
Gyro’s website page about project
Facebook photos
Instructables.com: “Using a hard drive to cut a record.” A very detailed step by step account
(Note: We’ve tidied up the formatting and structuring of Andrew/Gyro’s original informal post a little bit, for blog-legibility.)